In this article I discuss a big frustration electrical engineers
and electrical hobbyist face.
Why is it, that for simple circuits, the measurements are completely different from
calculations!!! Infact when writing my article on negative
resistance, as you would have seen - it happened again - along with the frustration :|
In my negative resistance circuit, the source voltage supplied by my wave generator was
set to 4V. The measured voltage when the generator was attached to the rest of the circuit
was however 1.6V
Soooo.... what is the source of the frustration? - Well we never question our tools! -
especially when they are some how digital based!
My theory is, we have been taught to think: In the digital world, there are plenty of opamps
and transistors. And like transistor circuits and opamp circuits - if a device's output
should have low resistance, for example a wave generator, its resistance would be
extra low. If a device's input should have high resistance, for example an
oscilloscope, its resistance would be extra high!
Now I'm not claiming this concept is false. However here is what to do after you confirm
your calculations and connections are 100% correct. First - make sure your probes from your
oscilloscope is set to the highest resistance (I set mine to ×10) and your probes from
the wave generator is set to the lowest resistance (I set mine to ×1).
We test again!
Wow - look at that! The output shot up to 44V! - from 4V to 44V!
And now the input...
...mmm no improvement.